In a vehicle side air bag device described in Patent Document 1, a side air bag includes a rear-side tube bag portion configured to extend in a vertical direction on a vehicle rear side relative to a vehicle-width outer end of a chest of a sitting occupant at the time when a side air bag is expanded and unfolded. Further, the side air bag includes a front-side tube bag portion configured to be placed on a vehicle front side relative to the rear-side tube bag portion and on a vehicle front side relative to the vehicle-width outer end of the chest of the sitting occupant and to extend in the vertical direction, at the time when the side air bag is expanded and unfolded. An upper part of the rear-side tube bag portion is placed on a lateral side of a shoulder of the sitting occupant so as to serve as a shoulder restraining portion that restrains the shoulder, and an upper edge of the front-side tube bag is placed at a position lower than a side of the sitting occupant on the vehicle front side relative to the shoulder restraining portion, and serves as an arm support portion on which an upper arm of the sitting occupant is placed.
That is, in the vehicle side air bag device, that shoulder of the sitting occupant which has a relatively high resistance is restrained by the shoulder restraining portion, while the upper arm of the sitting occupant is placed on the arm support portion, so as to prevent the upper arm from being placed between an air bag and that chest of the sitting occupant which has a relatively low resistance.
Examples of the prior art document related to the present invention include Patent Documents 2 to 4.